JPS5851894B2 - Optical fiber base material manufacturing equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for producing an optical fiber base material by a gas phase chemical reaction.

As a device for manufacturing optical fiber base materials, carrier gas and oxygen carrying a gaseous glass-forming compound and a compound for controlling the refractive index of glass are introduced into a quartz reaction tube that can be rotated by a predetermined flow rate. After heating the reaction tube with a heating burner moving along the length of the reaction tube to deposit the above compound in the form of a glass-forming oxide to a predetermined thickness as a cladding layer and a core forming layer, The introduction of oxygen and carrier gas is stopped, and the reaction tube is crushed and solidified using a heating burner to produce an optical fiber base material.

As shown in FIG. 1, the quartz reaction tube 1 is connected at both ends with a gas introduction side support tube 2 and a gas exhaust side support tube 3, which have a larger diameter than the reaction tube, in order to be installed in a rotating device. ing.

In the conventional optical fiber base material manufacturing apparatus, fine particles of unnecessary oxide 14 formed by the above-mentioned gas phase chemical reaction are deposited on the inner wall of the gas exhaust side support pipe 3 shown in FIG.
The flow rate of gas flowing through the reaction tube fluctuates depending on the oxide soot deposited, and the thickness of the deposited glass layer formed on the inner wall of the reaction tube cannot be precisely controlled.

Therefore, the oxide soot deposits were removed by scraping them out with a glass rod or the like, but this removal method took too much time and had the drawbacks of introducing impurities into the reaction tube.

The object of the present invention is to easily remove the oxide soot deposited on the inner wall of the exhaust side support tube, and to easily control the glass layer formed inside the reaction tube to be uniform.

That is, a gas composition for forming a glass layer is introduced from one end of the reaction tube, and the reaction tube is heated with a heating burner that moves along its longitudinal direction to vitrify the reaction product deposited inside the reaction tube. In the apparatus, an unnecessary deposit discharge pipe whose one end is connected to an exhaust means is installed in the exhaust side support pipe connected to the other end of the reaction tube.

The present invention also aims to provide a novel optical fiber base material manufacturing apparatus characterized in that this discharge pipe is attached via a reciprocating means so as to be moved in and out periodically in conjunction with the movement of a heating burner. be.

An embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 2 shows a schematic diagram of an apparatus for manufacturing an optical fiber base material according to the present invention.

As shown in the figure, an exhaust pipe 5 for discharging accumulated unnecessary oxide soot 4 is installed in an exhaust side support pipe 3 connected to a quartz reaction tube 1.

As for the material of the discharge pipe, a glass pipe is preferable from the viewpoint of chemical resistance and heat resistance.

The other end of this discharge pipe is connected to a flexible pipe 6 made of a material with strong chemical resistance, such as vinyl chloride, and the other end of the flexible pipe is connected to a partition plate 7 in the center and a It is connected to a container 9 having strong chemical resistance and having an exhaust port 8 connected to a pump.

Further, the oxide soot discharge pipe 5 is installed on a moving table 11 that is reciprocated by a motor 10 in the longitudinal direction of the reaction tube.

Here, the heating burner 12 moving in the longitudinal direction of the reaction tube is
While moving from the connection point A between the reaction tube 1 and the inlet side support tube 2 to the connection point B between the reaction tube 1 and the exhaust side support tube 3,
The gaseous glass-forming compound introduced from the support tube on the gas introduction side of the reaction tube is oxidized and deposited as a glass-forming oxide on the inner wall of the reaction tube.

Here, when the heating burner reaches point B from point A, the micro switch 13 is operated, the motor 10 connected to the switch is operated to move the movable table 11, and the discharge pipe 5 on the movable table 11 is moved. is inserted into the exhaust side support pipe as shown in FIG. absorb into.

The oxide soot thus sucked passes through the flexible tube 6 and is deposited at the bottom of the container 9 having the exhaust port 8.

While the heating burner moves from point B to point A, the discharge pipe 5 sucks out unnecessary oxide soot, and the heating burner moves from point B to point A.
When the point A is reached, the microswitch 14 is operated, the motor 10 is rotated in the opposite direction, and the movable stage is moved in the opposite direction, and the oxide soot discharge pipe 5 on the movable stage is
It is made to be pulled out from the exhaust side support pipe 3.

That is, while the heating burner is moving from point A to point B, the exhaust pipe 5 is moved outside the exhaust side support pipe 3 so that the flow rate of the glass forming gas introduced is not disturbed.

By continuously repeating the above operations, unnecessary oxide soot generated in the exhaust support pipe is removed, and therefore the flow rate of the introduced reaction gas is stabilized.

As described above, by using the optical fiber base material manufacturing apparatus according to the present invention, unnecessary oxide soot deposited in the exhaust side support pipe can be easily removed, and the flow rate of the introduced reaction gas can be stabilized. Therefore, the thickness of the glass deposited layer formed in the reaction tube can be easily controlled.

It also prevents impurities from being brought into the reaction tube.
The advantage is that an optical fiber base material with low optical transmission loss can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing how oxide soot is deposited on the exhaust side support pipe when manufacturing an optical fiber preform using a conventional device, and FIG. It is a figure showing a manufacturing device. 1: Reaction tube, 2: Gas inlet side support tube, 3: Gas exhaust side support tube, 4: Oxide soot, 5 Dioxide soot discharge tube, 6: Flexible tube, 7: Partition plate, 8: Exhaust mouth, 9
: Container, 10: Motor, 11: Moving table, 12: Heating burner, 13, 14: Micro switch, A: Connection point between reaction tube and gas inlet side support tube, B: Connection point between reaction tube and gas exhaust side support tube connection point.

Claims (1)

[Claims] 1. A gas composition for forming a glass layer is introduced from one end of the reaction tube, and the reaction tube is heated with a heating burner that moves along its longitudinal direction to vitrify the reaction product deposited inside the reaction tube. In the apparatus, an unnecessary deposit discharge pipe, one end of which is connected to an exhaust means, is reciprocated so as to be periodically inserted and removed in conjunction with the movement of the heating burner, into the exhaust side support pipe connected to the other end of the reaction tube. An apparatus for manufacturing an optical fiber base material, characterized in that the apparatus is installed via a moving means.